Bird Ecology Study Group, Nature Society (Singapore)

Sunday, July 31, 2005

ZEBRA DOVES - 1. Hatching of the first egg

ZEBRA DOVES - 1. Hatching of the first egg

I have been observing the activities around the nest of a pair of Zebra Doves (Geopelia striata) for the last two week. Every evening at around 5pm, the bird in the nest flew out and its mate flew in to take over the incubation duty. The night shift bird would then sit on the eggs right up to the next morning without ever leaving the nest. At around daybreak there should be another shift change. But for the last two weeks I was not able to witness the morning shift change. I was wondering whether the birds were on 24 hours incubation duty.

Then this morning I had a pleasant surprise.

I wasn't particularly keeping watch as in the past. At around 8 am when I was near the nest, the bird inside suddenly flew off. Within a few seconds its mate flew in. But instead of making itself comfortable in the nest, it picked up a piece of egg shell in its beak and immediately flew off. Three minutes later it flew in minus the shell and settled in the nest.

This is the day I have been waiting for - the hatching of one of the two eggs. The bird kept bending its neck downwards, making feeding movements. As with pigeons and doves, the Zebra Doves feed their chicks with crop milk.

Saturday, July 30, 2005

WHAT HAPPENED TO THE YELLOW-VENTED BULBULS' CHICK?

WHAT HAPPENED TO THE YELLOW-VENTED BULBULS' CHICK?

Last month a pair of Yellow-vented Bulbuls (Pycnonotus goiavier) built their nest among the branches of a Dracaena tree by my bedroom window. The convenience of the location led me to keep watch on the activities of the birds every day for the next few weeks. I set up my camera by the window. The curtains helped to shade me from being noticed by the birds. But the birds knew I was around. Every time I looked into the camera, the bird in the nest would face me, beak wide open.

It was an exciting period as I watched them incubating the egg (only one was laid) and looking after the chick.

During incubation, the birds did not sit in the nest continuously. Both parents visited the nest regularly. Each took turns to sit on the egg for about 10 to 15 minutes before flying off. This went on throughout the day. Only towards dusk would one of the birds stay in the nest, to remain there throughout the night. By dawn the duty bird left the nest but one or the other would return for short periods throughout the day. Unfortunately the sexes look alike so I could not distinguish between them.

One morning, 10 days after I spotted the nest, the egg hatched. The day-old blind chick was totally devoid of feathers. It remained flat on the bottom of the nest. There was no sign of the eggshell in the nest or on the ground around. The bird must have dumped it some distance away.

Throughout the day both parents flew in and out of the nest bringing food to feed the newly hatched chick. The chick responded to the parents' presence by opening its beak wide. After the food was transferred to the chick, the parent bird settled down in the nest, to fly off after a short while. Every 10 to 15 minutes one or the other bird flew in to feed the hungry chick. By the third day the chick was fed solid food of various insects and invertebrates. If the piece of food were too big for the chick to swallow, the parent bird would pull it out of the chick's throat and try breaking it into smaller pieces.

The parent birds were seen to constantly peck into the nest, probably removing bits and pieces of food not eaten by the chick. Or was it pecking at the ants in the nest? It was also possible that the bird were eating the excretion of the chick as, according to the literature, this contains undigested food.

One day, I was immediately below the nest when the parent bird noticed my presence. It suddenly took off and landed on the ground some distance away. It pretended to be hurt, flapping it wings to exaggerate its supposedly wounded condition. Naturally when I approached it, the bird moved further away, to subsequently fly off.

Unfortunately, after the chick was only four days old, tragedy struck. I saw the parent bird settling down for the night with the chick. But next morning the chick was nowhere to be seen. The nest was empty. It must have disappeared from the nest sometime during the night. Who or what was responsible, I do not know. Could it be crows? But then there were no crows at night or even during the early morning. Could it be a cat or a rat? Possible. Or a changeable lizard? Maybe, as there were a few around. Or it could be a snake or a squirrel even?

The birds were in shock that morning, flying in and looking puzzled. They took turns returning to the nest, looking around with their beaks wide open and even sitting in the nest for short periods before flying off. This they did for some time before the truth must have dawned on them that the chick was really gone and would not appear ever again. Then they finally left the scene.

Monday, July 25, 2005

WHY BIRD ECOLOGY?

WHY BIRD ECOLOGY?

It all started when a pair of Yellow-vented Bulbuls (Pycnonotus goiavier) built their nest among the branches of a tree in my garden. This is one of the commonest birds around urban Singapore and you don't need to be a birdwatcher to recognise it. Eventually the eggs hatched and the parent birds began feeding the chicks. I was curious to find out the breeding details of this bulbul. Like, how many days does it takes for the eggs to hatch? Do both parent birds help in the incubation of the eggs? What do the parents feed the chicks with? How many days before the chicks leave the nest? These and many other questions raced through my mind. And they needed answers. I have G.C. Maddoc’s “An Introduction to Malayan Birds” published in 1956. There are some ecological data but many of my questions could not be answered. The 1987 book, “Birds of Singapore” by Christopher Hails again carry limited ecological information. There are many guidebooks in the market but these are useless unless you wish to identify birds. The available books proved no help to me.

So I trawled the net once again. Even the net was not helpful. Of the 16,800 sites located by the search engine for Yellow-vented Bulbul, only two had any potential. The first was the web page set up in 2001 by Ria Tan, author of the Chek Jawa guide book. The second was that of the Nature Photographic Society (Singapore). This had images and ecological notes on hatching, chicks, etc., information that was current. The other 16,798 sites were of no help, containing trip reports where bulbuls were sighted or where images were given. Even the Oriental Bird Club's site or that of the Nature Society (Singapore) did not help.

So what happened to the information gathered by the many birders operating from Singapore over the last two decades? Surely, much data on such a common bird would have been recorded.

Have these ever been published or even made available in web pages that I do not know of? Or are they stored in the memories of birders, to be eventually lost to ornithology? I am sure many others are equally hungry for information on the breeding behaviour of birds. Is it possible then for such information to be made available to the public at large? After all, knowledge not shared is knowledge lost.

My next experience was when a pair of Pink-necked Pigeons (Treron vernans) nested in my garden. Again I faced a blank wall. The literature as well as the net proved not helpful. Ria Tan's page again gave some information, and she is not even a birder. There was also the page set up by the Sungei Buloh Nature Park. The information provided by these two pages, although current, was incomplete.

So what is a sometime-birder, who is not an ornithologist, to do?

I am now convinced that ecological information of our local birds is sketchy at best - because experienced birdwatchers are just looking at birds and not at their behaviour.

We cannot wait for ornithologists, the so-called biologically qualified people, to deliver the goods. After all how many ornithologists are there in Singapore? One? Two? And are there actually three? With biology moving from the traditional fields to the "life sciences" where emphasis is on the molecular aspects, ornithologists are becoming an endangered species here.

But then we have hundreds of birdwatchers, many very experienced. Should not these birdwatchers start collecting avian behavioural data at the same time? By all means bird watch, but please also behaviour watch. Take notes while out bird watching and share your information with others. If possible publish your findings so that others can share your experience.

The Bird Ecology Study Group was thus formed to encourage the study of bird behaviour. The group hopes to disseminate information on what bird behaviour is all about and how to conduct such studies. In the process we hope to encourage birders who are not satisfied to be just recreational birdwatchers, to become serious students of ornithology. In this way they can contribute substantially to the avian biology of Singapore.

The latest and most updated bird book for this area is David Wells' “The Birds of the Thai-Malay Peninsula (Vol. I: Non-passerines)”. Open the pages and what do you find? Numerous entries like "No Information", "No Data", "Not Described", "Non Reported" and "Not Recorded".